Respiratory apparatus

ABSTRACT

A flow generator for generating a flow of pressurized breathable gas includes a cylindrical housing and a motor supported in the housing. The motor has a shaft having a first end and a second end opposite the first end. The shaft is generally coincident with an axis of the motor. A first impeller is attached to the first end of the shaft and a second impeller is attached to the second end of the shaft. A stator directs an air flow from the first impeller back towards the motor axis. The housing includes an inlet adjacent the first end of the shaft having an inlet axis generally coincident with the motor axis and at least one outlet between the first and second impellers. The at least one outlet has an outlet axis generally tangential to the motor axis. An apparatus for delivering a flow of pressurized breathable gas to a patient includes a flow generator and a casing to contain the flow generator. The casing is configured to engage a part of the patient&#39;s body, for example the top of the patient&#39;s head, and/or to receive a strap adapted to encircle, for example, the patient&#39;s arm or chest. The apparatus further includes at least one delivery conduit to convey the flow of pressurized breathable gas and a patient interface to receive the flow of pressurized breathable gas from the at least one delivery conduit and deliver it to the patient&#39;s airways.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Application 61/024,993, filedJan. 31, 2008, the entire contents of which are incorporated herein byreference.

INCORPORATION BY REFERENCE

The entire contents of WO 2008/028247 A1, are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a respiratory apparatus for deliveringa flow of pressurized breathable gas to a patient.

BACKGROUND OF THE INVENTION

Obstructive Sleep Apnea (OSA) is a sleep breathing disorder (SBD). Forthose who have OSA, when they sleep the soft tissue in their throat andairway relax and collapse thus blocking the airway and preventingairflow to the lungs. This cessation of breathing, known as an apnea,can last for up to one minute before the blood oxygen levels reach acritical point where the patient has an arousal and their airwayreopens. Most OSA suffers do not remember these arousals, however eacharousal places extra strain on a patient's heart and destroys thequality of their sleep.

The treatment for OSA may include continuous positive airway pressure(CPAP). CPAP involves the patient wearing a nasal or facemask thatdelivers positive pressure into the patients airway. This acts as apneumatic splint and holds the patients airway open to prevent apneas.

A typical respiratory apparatus for CPAP therapy includes a flowgenerator, including for example an air blower, that generates a flow ofpressurized breathable gas, e.g. air, to a patient interface configuredto be worn by the patient in sealing engagement with the patient's face.The patient interface may be, for example, a nasal mask, a full facemask, or nasal pillows. The flow generator and the patient interface areconnected by a tube that delivers the flow to the patient interface.

The typical respiratory apparatus for CPAP therapy has severaldisadvantages. The patient interface and tube tend to be bulky, and thetube may be rather long, e.g. from about 2-3 m in length. The headgearused to maintain the patient interface in contact with the patient'sface may also be bulky and/or complicated to correctly put on and/oradjust. These factors may make a patient reluctant to start CPAPtherapy. These factors may also make it difficult for the patient tofind a comfortable sleeping position. During sleep, the patient maychange position, and the tube may exert a force, i.e. tube drag, on thepatient interface which may disrupt the seal between the patientinterface and the patient's face. This may result in a leak in thepatient interface, which reduces the efficacy of the treatment. Leakagefrom the patient interface may also irritate the patient, or thepatient's sleeping partner, thus further damaging the quality of thepatient's sleep.

Patients using a typical CPAP apparatus for therapy may also find itdifficult to travel with the apparatus. The flow generator, tube, andmask may be difficult to pack in luggage, and may take up a lot of roomwithin the luggage. The patient may also find it difficult to use theapparatus away from home as the flow generator typically includes apower cord that must be plugged into a power source, e.g. an AC wallsocket, which may not be accessible, or available, at the location thepatient is visiting.

SUMMARY

One aspect relates to enhancing the treatment delivery by a device thatincorporates all, or most, of the components of a CPAP system into asingle wearable device. For example, the mask and flow generator may beintegrated into a mask system worn by the patient. The flow generatormay be incorporated into a headgear configured to support the mask. Thisaspect provides several advantages over current CPAP systems.

Another aspect relates to providing a CPAP system that is streamlined,for example by the removal of the flow generator power cable and/or theair delivery tube. According to this aspect, the patient has increasedfreedom of movement, including during sleep. The elimination of the tubemay lead to reduction in leaks due to a reduction in destabilizingforces on the patient interface.

Yet another aspect relates to reducing the size of a blower in a flowgenerator blower assembly as a result of lower power requirements, whichare possible due to the reduction, or elimination, of head loss in theflow in an air delivery tube.

A further aspect relates to a CPAP system that is less obtrusive andmore intuitive to use for the patient. The CPAP system may beanthropometrically designed to engage the wearer's head and face in amanner readily and easily understood by the patient.

An even further aspect relates to a CPAP system that is portable and maybe used by the patient when away from home. The CPAP system may beconfigured to contain its own power supply, e.g. a battery or batterypack. The CPAP system may also be configured to be received in a dockingstation to recharge the power supply.

Still another aspect relates to a flow generator that is reduced in sizecompared with stand alone flow generators. The flow generator may beincorporated into a housing that is configured to engage the patient'shead. Such a flow generator may operate on a rechargeable power supply,e.g. a battery or battery pack, for the entirety of the patient's sleepcycle. The flow generator may also generate less noise, and be moreefficient, than stand alone flow generators.

According to a sample embodiment, a flow generator for generating a flowof pressurized breathable gas comprises a cylindrical housing; a motorsupported in the housing, the motor having a shaft having a first endand a second end opposite the first end, the shaft being generallycoincident with an axis of the motor; a first impeller attached to thefirst end of the shaft; a second impeller attached to the second end ofthe shaft; and a stator that directs an air flow from the first impellerback towards the motor axis. The housing comprises an inlet adjacent thefirst end of the shaft and having an inlet axis generally coincidentwith the motor axis, and at least one outlet between the first andsecond impellers, the at least one outlet having an outlet axisgenerally tangential to a circumference of the cylindrical housing.

According to another sample embodiment, an apparatus for delivering aflow of pressurized breathable gas to a patient comprises a flowgenerator, for example as discussed in the preceding paragraph, and acasing to contain the flow generator. The apparatus further comprises apower supply for the flow generator; at least one delivery conduit toconvey the flow of pressurized breathable gas; and a patient interfaceto receive the flow of pressurized breathable gas from the at least onedelivery conduit and deliver it to the patient's airways

Other aspects, features, and advantages will become apparent from thefollowing detailed description when taken in conjunction with theaccompanying drawings, which are a part of this disclosure and whichillustrate, by way of example, principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousembodiments described herein. In such drawings:

FIG. 1 schematically illustrates a respiratory apparatus according to asample embodiment;

FIG. 2 schematically illustrates a respiratory apparatus according toanother sample embodiment;

FIG. 3 schematically illustrates a flow generator housing or casing fora respiratory apparatus according to a sample embodiment;

FIG. 4 schematically illustrates a blower assembly of a flow generatorfor a respiratory apparatus according to a sample embodiment;

FIG. 5 schematically illustrates a side elevation view of the blowerassembly of FIG. 4;

FIG. 6 schematically illustrates an opposite side elevation view of theblower assembly of FIG. 4;

FIG. 7 schematically illustrates a front side election view of theblower assembly of FIG. 4;

FIG. 8 schematically illustrates a bottom view of the blower assembly ofFIG. 4;

FIG. 9 a schematically illustrates a perspective view of the blowerassembly of FIG. 4;

FIG. 9 b schematically illustrates an exploded assembly view of theblower assembly of FIG. 9 a;

FIG. 10 schematically illustrates a cross-section of the blower assemblyof FIG. 4;

FIG. 11 schematically illustrates a cross-section of the blower assemblyof FIG. 4;

FIG. 12 schematically illustrates a cross-section of a first impeller ofthe blower assembly of FIG. 4;

FIG. 13 schematically illustrates a perspective view of the firstimpeller of FIG. 12;

FIG. 14 schematically illustrates a stator of the blower assembly ofFIG. 4;

FIG. 15 schematically illustrates a second impeller of the blowerassembly of FIG. 4;

FIG. 16 schematically illustrates a respiratory apparatus according toanother sample embodiment;

FIG. 17 schematically illustrates a respiratory apparatus according toanother sample embodiment;

FIG. 18 schematically illustrates a flow generator according to anothersample embodiment;

FIGS. 19 and 20 schematically illustrate a respiratory apparatusincorporating the flow generator of FIG. 17; and

FIG. 21 schematically depicts a respiratory apparatus according toanother sample embodiment.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The following description is provided in relation to several embodimentswhich may share common characteristics and features. It is to beunderstood that one or more features of any one embodiment may becombinable with one or more features of the other embodiments. Inaddition, any single feature or combination of features in any of theembodiments may constitute additional embodiments.

Respiratory Apparatus First Embodiment

Referring to FIG. 1, a respiratory apparatus for delivering a flow ofpressurized breathable gas to a patient 2, for example to treat SBD,such as OSA, comprises a flow generator 4 to generate the flow ofpressurized breathable gas. The flow generator 4 is contained in a flowgenerator housing or casing 6 that is anthropometrically configured toengage the head of the patient 2. As shown in FIG. 1, the flow generatorhousing 6 is configured to engage the top of the patient's head topermit the patient to sleep on the patient's side without disturbing thepositioning of the flow generator housing 6. As shown in FIG. 1, theflow generator housing may have a curvature in the back to frontdirection of the housing, and a curvature in a lateral direction, i.e.in a direction from one side of the patient's head to the other side.

The flow generator 4 delivers a flow of pressurized breathable gasthrough delivery tubes or conduits 8 which are connected to the flowgenerator housing 6 for receipt of the flow of pressurized breathablegas. The flow of pressurized breathable gas is delivered by the deliveryconduits 8, which extend from the flow generator housing 6 along thesides of the face of the patient 2, to a patient interface 10 that is incontact with the nasal passageways of the patient 2. As shown in FIG. 1,the patient interface 10 may support nasal pillows or prongs 12 whichare in sealing contact with the nares of the patient's nose. It shouldbe appreciated, however, that the delivery conduits 8 may deliver theflow of pressurized breathable gas to a nasal mask which covers only thenose of the patient. As another example, the delivery conduits 8 may beconnected to a full face mask which covers the nose and mouth of thepatient. As an even further example, the delivery conduits 8 may beconnected to a patient interface that includes a mouth covering portionhaving nasal pillows or prongs extending from the mouth covering portionfor sealing engagement with the nose of the patient. It should be evenfurther appreciated that the patient interface may include nasalcannulae which do not sealingly engage with the nose of the patient.

The conduits 8 may be formed of soft material, for example siliconerubber, to isolate vibrations from the flow generator 4. The conduits 8may also be connected to the flow generator by a connector configured toisolate vibrations, for example a soft grommet or a bellows typeconnector. The conduits 8 may also be the conduits as disclosed in U.S.Patent Application Publication 2008/0060649 A1, the entire contentsbeing incorporated herein by reference.

Respiratory Apparatus Second Embodiment

Referring to FIG. 2, a respiratory apparatus according to another sampleembodiment includes strap attachment portions 14 provided on thedelivery conduits 8. A strap, or headgear system, may be connected tothe strap attachment portions to provide additional securement of therespiratory apparatus to the head of the patient. As shown in FIG. 2,the flow generator housing 6 may be configured to extend towards theback of the head of the patient 2, but may not extend as far forward onthe head of the patient 2 as the flow generator housing 6 of the sampleembodiment of FIG. 1.

Referring to FIG. 3, the flow generator housing 6 may be configured tosupport a voltage regulator 16, a motor controller 18 and a power source20. The power source 20 may comprise a battery, or a plurality ofbatteries. For example, the battery or batteries may be configured aslithium polymer batteries having a volumetric energy density of about250-530 Wh/L, for example about 270 to 400 Wh/l, as another exampleabout 330 Wh/l and a gravimetric energy density of about 150-200 Wh/kg,for example about 155 to 175 Wh/kg, as another example about 163 Wh/kg.Such a battery would have, for example, a battery volume of 112 cm² anda weight of 225 g. The lithium polymer battery may comprise 32 lithiumpolymer battery cells that would provide approximately 8 hours of powerto an electric motor of a blower assembly of the flow generator 4 forgenerating a flow of about 40-60 l/min, for example, 50 l/min at apressure in a range of about 2-12 cm H₂O, for example about 6 cm H₂O.The battery cells may be flexible and thus may be curved for insertioninto the housing 6 which may be curved to match the shape of the top ofthe patient's head.

The lithium polymer battery may have a life cycle of approximately 500charges. The flow generator housing 4 may be provided with a dockingstation configured to charge the battery when the housing 4 is placed inthe station.

Flow Generator and Blower Assembly

Referring to FIGS. 4 and 5, the flow generator 4 comprises a blowerassembly 22. The blower assembly 22 comprises a blower assembly upperhousing 24 and a blower assembly lower housing 34. A blower assemblyinlet 26 is provided in the upper housing 24. It should be appreciatedthat the use of the terms “upper” and “lower” refer to the orientationof the blower assembly housing shown in the drawings and not necessarilyto any required orientation of the blower assembly. As shown in FIGS.4-9 b, the blower assembly 22 comprises a first outlet 28 and a secondoutlet 30 on opposite sides of the lower housing 34. An electricalconnector 32 is provided between the upper housing 24 and the lowerhousing 34 to provide power to an electric motor 44 (FIG. 10).

Referring to FIG. 10, the blower assembly 22 comprises the upper housing24 and the lower housing 34 and a middle housing 40 provided between theupper housing 24 and the lower housing 34. A stator 38 is supported onthe middle housing 40. The electric motor 44 is supported by the stator38.

The electric motor 44 includes a shaft 45 that extends from oppositesides of the electric motor 44. The shaft 45 may be generally coincidentwith an axis of the motor 44. A first impeller 36 is connected to theshaft 45 for rotation with the shaft upon actuation of the electricmotor 44. A second impeller 42 is connected to the opposite side of theshaft 45 and thus the opposite side of the motor for rotation with theshaft 45 upon actuation of the electric motor 44. The motor 44 may beselected from a variety of commercially available motors, for examplefrom the motors supplied by Maxon Motor of Switzerland.

Upon actuation of the electric motor 44, the shaft 45 rotates and causesrotation of the first impeller 36 and the second impeller 42. As shownin FIGS. 10 and 11, rotation of the impellers 36, 42 causes a flow F ofair into the inlet 26 of the blower assembly 22. The flow enters theupper housing 24 through the inlet 26 and proceeds around the firstimpeller 36 and is forced down towards the stator 38. The flow thenflows around the stator 38 and is forced down through the middle of thesecond housing 40 towards the second impeller 42. The second impeller 42forces the flow back up over the periphery of the middle housing 40 andout through the first outlet 28 and the second outlet 30.

The inlet 26 of the blower assembly 22 has an axis that is generallycoincident with the axis of the electric motor 44. The axis of the firstoutlet 28 and the axis of the second outlet 30 are generally tangentialto circumference of the housings 24, 34 and generally perpendicular tothe axis of the blower assembly 22 and/or the motor 44. The use of theaxially coincident inlet 26, the tangential outlets 28, 30, and the twoimpellers 36, 42 provides a flow path that is folded back on itself, asshown in FIGS. 10 and 11, which utilizes what would otherwise be deadspace in the blower assembly and thus reduces the overall size of theblower assembly 22. The reduced size of the blower assembly 22 providessmaller gaps and apertures along the flow path which reduces, oreliminates, turbulence and noise, and enables a low flow Reynolds numberfor the flow F from the blower assembly 22. The blower assembly 22 maybe adapted such that the path of the flow F extends along a firstsection from the inlet 26 having an axis that is generally paralleland/or coincident to the axis of the electric motor 44. The flow F isthen directed, along a second section, radially outwardly with regard tothe axis of the electric motor 44 by the first impeller 36. The flow Fthen extends along a third section, from the outer circumference of thefirst impeller 36 in a generally axial direction, and generally paralleland in the same general direction as the flow's initial direction whenentering the inlet 26 along the first section. The flow F then extends,along a fourth section, radially inwardly along the stator 38.Accordingly, the flow F is folded back on itself at least once, forexample from a radial outward direction around the circumference of thefirst impeller 36 along the second section to a radial inward directionalong the fourth section.

The flow F extends radially inwardly along the stator 38 generally up tothe outer circumference of the motor 44. The flow F then extends along afifth section that extends generally axially with respect to the axis ofthe motor 44 and along the motor in generally the same direction as thefirst section. The fifth section of the flow F may be defined betweenthe motor 44 and the inner circumference of the middle housing 40. Theflow F then extends a long a sixth section and is directed radiallyoutwardly with respect to the axis of the motor 44 by the secondimpeller 42. Accordingly, the flow F is folded back on itself at leastonce, and possibly a second time, i.e. from a radial inward directionalong stator 38 and along the fourth section to a radial outwarddirection along the second impeller 42 and the sixth section. At theouter circumferential end of the second impeller 42 the flow F extends,along a seventh section, generally axially upwardly towards the firstand/or second outlet 28, 30. Thus the flow F is folded back on itself atleast once, and possibly three times. The flow path F may be meandering.It should be appreciated that the description of the flow F relates tothe cross sectional views shown in FIGS. 10 and 11. As shown, the flow Fmay be generally radially symmetrical.

The outlets 28, 30 may be elliptical or oval. The use of elliptical oroval outlets reduces, or minimizes, the size of the outlets and allowsthe axial dimension, i.e. height, of the blower assembly 22 to bereduced, or minimized. The use of elliptical or oval outlets provides asufficient cross sectional area to permit the flow to exit the blowerassembly and also reduces sharp corners in the blower assembly. Asshown, for example in FIGS. 4, 8, 9 a, and 9 b, there are two outlets28, 30 symmetrically provided on the blower assembly 22. The use of twosymmetrical outlets provides more outlet flow area for a given axialheight than a single outlet, and lowers conducted noise. It should beappreciated that more than two outlets may be provided. It should alsobe appreciated that the outlets may have a 360° rotational symmetry.

Referring to FIG. 12, the first impeller 36 includes a first impellerdisk 46. A motor mounting portion 48 is configured for mounting thefirst impeller 36 to the electric motor shaft 45. As shown in FIG. 13,the motor mounting portion 48 includes an aperture 50 configured toreceive the electric motor shaft 45. A plurality of vanes 52 areprovided on the first impeller disk 46 to generate the flow F uponrotation of the first impeller 36. The vanes 52 direct the flow radiallyto the periphery of the first impeller 36 as shown in FIGS. 10 and 11.The first impeller 36 generates a flow F that is initially in the axialdirection of the electric motor 44.

As shown in FIG. 13, the vanes 52 of the first impeller 36 are generallystraight. However, it should be appreciated that the vanes 52 may becurved. As also shown in FIG. 13, the vanes 52 may have a varyingheight. The height of the vanes may be largest toward the center of thefirst impeller disk 46 and may be smallest at the outer periphery orcircumference of the first impeller disk 46. The height of the vanes for52 may be related to the diameter of the first impeller disk 46 forproviding a desired flow. The height of the vanes 52 may be optimizedfor the selected diameter of the first impeller disk 46 to furtherreduce the overall size of the blower assembly 22. The vanes 52 may beconfigured such that the height of the vanes 52 at their tips (i.e. atthe circumferential edge of the disk 46) are the minimum height thatdoes not choke the flow F. The “choke” is related to the cylindricalsurface of the disk 46 at the circumferential edge, i.e. the outer edgesof the vanes 52, and the axial height of the vanes 52 at thecircumferential edge of the disk 46. In other words the “choke” isrelated to a cylinder of diameter equal to the outer diameter of disk 46and which has an axial dimension (height) equal to the height of thevanes 52 at the periphery of disk 46. The lower the height of the vanes52, the lower the Reynolds number and therefore the lower the turbulencenoise.

Referring to FIG. 14, the stator 38 comprises a stator disk 54 and amotor mounting portion 56 to mount the stator 38 to the electric motor44. A plurality of vanes 58 are provided on the stator disk 54. As shownin FIG. 14, the vanes 58 are curved to fold the flow F delivered fromthe first impeller 36 back towards the center of the blower assembly,i.e. back toward the electric motor 44. The vanes 58 then direct theflow F in the direction of the axis of the electric motor 44 through themiddle housing 40 toward the second impeller 42, as shown in FIGS. 10and 11.

Referring to FIG. 15, the second impeller 42 comprises a second impellerdisk 60 and a motor mounting portion 62 configured to connect the secondimpeller 42 to the shaft 45 of the electric motor 44. A plurality ofvanes 64 are provided on the second impeller disk 62 for directing theflow F around the middle housing 40 and out the first outlet 28 and asecond outlet 30, as shown in FIGS. 10 and 11. By folding the flow Fback toward the electric motor 44, and by directing it axially along thecircumference of the electric motor 44 before folding the flow F back,radially outwardly be the second impeller 42, the flow F cools the motor44 and is heated by passing the motor 44. The vanes 64 of the secondimpeller disk 62 may be configured in a manner similar to the vanes 52of the first impeller disk 46. As shown in FIGS. 9 b, 10 and 11, theinner ends of the vanes 64 define a diameter that is larger than thediameter of the motor 44. this allows the vanes 64 to sit, at leastpartly, at the same axial position as the lower section of the motor 44,which reduces the axial height of the blower assembly 22.

The blower assembly may have a width of about 45-60 mm, for exampleabout 50-55 mm, as another example about 52 mm, and a height of about20-30 mm, for example about 23-27 mm, as another example about 25 mm.The motor may have a width of about 15-25 mm, for example about 17-23mm, as another example about 20 mm, and a height of about 15-20 mm, forexample about 17 mm. The motor may be brushless and deliver about 1-5 Wshaft power, for example about 3 W. The motor may weigh about 10-20 g,for example about 13-17 g, as another example about 15 g. The blowerassembly may provide a flow of about 40-60 l/min., for example about45-55 l/min, as another example about 50 l/min., at a pressure of about2-12 cm H₂O, for example about 4-8 cm H₂O, as another example about 6 cmH₂O. It should be appreciated that these flow and pressure ranges areexamples and the flow generator may be scaled to provide flow andpressure ranges other than the examples provided herein.

The housing of the blower assembly may be configured to suppress noisegenerated by the motor 44. For example, a gel layer may be providedbetween the upper housing 24 and the lower housing 34, and/or a gellayer may be provided between the stator 38 and the motor 44 to dampvibrations and/or noise generated by the motor 44.

Other modifications that may be made to the blower assembly includeproviding bearings to the housing 24, 34 instead of the motor 44, asdisclosed in U.S. Patent Application Publication 2008/0304986 A1, theentire contents of which are incorporated herein by reference, adding amagnet(s) to the impeller(s), and/or configuring the motor as an axialgap motor, for example as disclosed in WO 2007/134405 A1, the entirecontents of which are incorporated herein by reference.

It should also be appreciated that other flow generator and blowerassemblies may be used in the sample embodiments discussed herein. Forexample, the flow generator and blower assemblies disclosed in U.S.application Ser. No. 29/274,504, 29/274,505, and 29/274,506, each filedApr. 27, 2007, and WO 2007/048206 A1, the entire contents of each beingincorporated herein by reference, may be used. As another example, theflow generator and blower assemblies disclosed in U.S. application Ser.Nos. 29/274,504, 29/274,505, and 29/274,506, filed Apr. 27, 2007, 2006,and WO 2007/048205 A1, the entire contents of which are incorporatedherein by reference, may be used.

Respiratory Apparatus Third Embodiment

Referring to FIG. 16, a respiratory apparatus according to anothersample embodiment comprises a flow generator 4 provided in a flowgenerator housing 6 configured to engage the head of the patient, forexample the crown of the patient's head. The flow generator 4 isconfigured to deliver a flow of pressurized breathable gas to deliveryconduits 8 which are configured to extend from the flow generator alongthe sides of the face of the patient to a patient interface 10. Thepatient interface may include nasal pillows or prongs, a nasal mask, afull face mask, or cannulae.

Power is provided to the flow generator 4 by a power supply andcontroller 66 that is connected to the flow generator 4 by an electricalconnector 68, for example a cable. The power supply/controller 66 may beconfigured to be docked in a battery charger, or may include anattachment that allows for charging of the power supply and controllerfrom a voltage source, for example a common household 120 volt ACsocket, or a 12 volt car battery charging outlet. The remainingconfiguration and features of the flow generator and blower assembly,respectively, may correspond to those discussed and shown with respectto the preceding and following embodiments.

Respiratory Apparatus Fourth Embodiment

Referring to FIG. 17, a respiratory apparatus according to anothersample embodiment may comprise a headgear 80 that may take the form of,for example, a skull cap. A pair of ear covering portions 82 may beprovided as well as a head covering portion 88. A head circling band 90may be provided between the ear covering portions 82 and the headcovering portion 88. A pair of straps, e.g. chin straps, 84, 86 may beprovided to the ear covering portions 82 to secure the headgear 80 tothe patient.

The flow generator may be provided in the headgear 80, for example inthe head covering portion 88. The power supply (e.g. the battery, orbatteries, including the flexible cells) and the control electronics(e.g. the voltage regulator and/or the motor controller) may also beprovided in the headgear 80, for example in the head covering portion 88or the ear covering portion(s) 82. The flow generator, the power supplyand the control electronics may be encased in foam or other cushioningmaterial to improve the comfort of the headgear. The battery cells maybe distributed about the headgear 80 to spread the weight of the powersupply throughout the headgear to improve comfort, reduce, or minimizethe height of the apparatus, and increase, or maximize, the stability ofthe apparatus.

Respirator Apparatus Fifth Embodiment

Referring to FIGS. 18-20, a respiratory apparatus according to anothersample embodiment comprises a flow generator 4 comprising a flowgenerator housing or casing 6. The flow generator 4 may include a blowerassembly as previously described. The flow generator housing 6 comprisesslots 70 configured to receive a band or strap 72 as shown in FIG. 18.The band or strap 72 may be configured to encircle the chest or arm ofthe patient to support the flow generator 4 at a position spaced fromthe head of the patient. A delivery tube or conduit 74 is configured tobe connected to the flow generator 4 at a first end and configured to beconnected to a patient interface 10 at a second end. The delivery tubeor conduit 74 may be a retractable tube or conduit that is flexible andextensible to accommodate movement of the patient's head, and thusmovement of the patient interface 10. Such a retractable tube isdisclosed in U.S. application Ser. No. 12/211,896, filed Sep. 17, 2008,the entire content being incorporated herein by reference. The patientinterface may be held in contact with the face of the patient by aheadgear system 76.

As shown in FIG. 19, the band, or strap, 92 may be configured to beintegrally formed with the flow generator casing 6. Alternatively, theband or strap may be separately formed and passed through the slots 70in the flow generator casing 6. The respiratory apparatus can besegmented into the respective elements. For example, the power supply(e.g. battery cells or pack) and the control electronics (e.g. thevoltage regulator and/or motor controller) may be located to the leftand/or right of the flow generator casing 6 and connected by a flexiblejoint, such as a cable. This permits a more custom fit to the patient.

As shown in FIGS. 19 and 20, the blower assembly housing may differ fromthe housing disclosed in FIGS. 4-16 in that the blower assembly housingmay include a single outlet tangential to the blower assembly inlet. Itshould be appreciated, however, that the sample embodiment shown inFIGS. 18-20 may be provided with a pair of outlets, and a pair ofdelivery tubes or conduits which may deliver the flow of pressurizedbreathable gas to a patient interface having two inlets, for example aninlet on each side of the patient interface. Such a patient interface isdisclosed, for example, in WO 2005/063328 A1, assigned to ResMed Ltd.

The flow generator housing 6 may be configured to support the blowerassembly 22, the power source 20, e.g. the battery or battery pack, andcontrol circuitry for operation of the electric motor of the blowerassembly.

Referring to FIG. 21, a variation of the sample embodiment of FIGS.18-20 may include a concentric air inlet tube 78 surrounding the airdelivery tube 74. If the flow generator is worn beneath the patient'sbed clothes, e.g. pajamas, the concentric air inlet tube may be placedoutside the patient's bed clothes to draw fresh air into the flowgenerator housing.

In the sample embodiments described above, the flow generator may beturned on and off using a switch. It should also be appreciated that theflow generator may be turned on using ResMed's SMART START® control.

Respiratory Apparatus Sound Levels

The sample embodiments of the respiratory apparatus disclosed herein maybe configured so that the noise level is sufficiently low to allowpatients to sleep. In general, typical flow generators are oftenconfigured such that the sound power emitted is about 25 dB based ontesting 1 meter away at the front of the device. However, the sampleembodiments of the respiratory apparatus disclosed herein are configuredto be placed on the user's person, e.g. on the head, an arm, the chest.This proximity of the flow generator to the user may result in anincreased sound level experienced by the user, for example by about 10dB(A). In addition, the sample embodiments disclosed herein may includeless insulation around the blower assembly of the flow generator, whichmay further increase the sound level experienced by the user, forexample by about another 10 dB(A). For comparison, a flow generator suchas that disclosed in U.S. Patent Application Publication 2008/0304986A1, the entire contents of which are incorporated herein by reference,comprising no insulation emits about 52 dB(A) sound power when runningat 10 cm H₂O air pressure.

The sample embodiments of the respiratory apparatus disclosed herein maycomprise insulating material within the headgear, mask, blower assembly,and/or flow generator casing, and/or a muffler, to reduce the soundpower emitted. For example, the headgear may be configured to reduce thesound power emitted by about 5-10 dB(A). The sample embodiments of therespiratory apparatus disclosed herein may emit a sound power of betweenabout 10-100 dB(A), for example about 10-65 dB(A), as another exampleabout 10-50 dB(A), as a further example about 20-40 dB(A), and as aneven further example less than about 25 dB(A), when the respiratoryapparatus is providing a flow at about 10 cm H₂O.

In this specification, the word “comprising” is to be understood in its“open” sense, that is, in the sense of “including”, and thus not limitedto its “closed” sense, that is the sense of “consisting only of.” Acorresponding meaning is to be attributed to the corresponding words“comprise”, “comprised” and “comprises” where they appear.

The term “air” will be taken to include breathable gases, for exampleair with supplemental oxygen. It is also acknowledged that the blowersdescribed herein may be designed to pump fluids other than air.

While the invention has been described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the invention. Also, the various embodiments described abovemay be implemented in conjunction with other embodiments, e.g., aspectsof one embodiment may be combined with aspects of another embodiment torealize yet other embodiments. Further, each independent feature orcomponent of any given assembly may constitute an additional embodiment.

Furthermore, each individual component of any given assembly, one ormore portions of an individual component of any given assembly, andvarious combinations of components from one or more embodiments mayinclude one or more ornamental design features. In addition, while theinvention has particular application to patients who suffer from OSA, itis to be appreciated that patients who suffer from other illnesses(e.g., congestive heart failure, diabetes, morbid obesity, stroke,barriatric surgery, etc.) can derive benefit from the above teachings.Moreover, the above teachings have applicability with patients andnon-patients alike in non-medical applications.

1. A flow generator for generating a flow of pressurized breathable gas,comprising: a cylindrical housing; a motor supported in the housing, themotor having a shaft having a first end and a second end opposite thefirst end, the shaft being generally coincident with an axis of themotor; a first impeller attached to the first end of the shaft; a secondimpeller attached to the second end of the shaft; and a stator thatdirects an air flow from the first impeller back towards the motor axis,wherein the housing comprises an inlet adjacent the first end of theshaft and having an inlet axis generally coincident with the motor axis,and at least one outlet between the first and second impellers, the atleast one outlet having an outlet axis generally tangential to acircumference of the cylindrical housing.
 2. A flow generator accordingto claim 1, wherein the cylindrical housing comprises a firstcylindrical housing segment and a second cylindrical housing segment. 3.A flow generator according to claim 1, wherein the inlet is provided inthe first cylindrical housing segment and the at least one outlet isprovided in the second cylindrical segment.
 4. A flow generatoraccording to claim 1, wherein the first and second impellers comprisestraight vanes.
 5. A flow generator according to claim 1, wherein thefirst and second impellers comprise curved vanes.
 6. A flow generatoraccording to claim 1, wherein the vanes have a varying height.
 7. A flowgenerator according to claim 6, wherein the height of the vanes of thefirst impeller at a circumferential edge of the first impeller is aminimum height that does not choke the flow.
 8. A flow generatoraccording to claim 2, further comprising: a third housing segmentintermediate the first and second housing segments, wherein the statoris supported by the third housing segment and motor is supported by thestator.
 9. A flow generator according to claim 8, further comprisingnoise and/or vibration dampening material between the motor and thestator and/or between the first and second housing segments.
 10. A flowgenerator according to claim 9, wherein the noise and/or vibrationdampening material comprises a gel.
 11. A flow generator according toclaim 1, wherein the motor is a brushless motor.
 12. A flow generatoraccording to claim 1, wherein the motor is an axial gap motor.
 13. Aflow generator according to claim 11, wherein the motor is configured todeliver about 1-5 W of power.
 14. A flow generator according to claim11, wherein the motor is configured to deliver about 3 W of power.
 15. Aflow generator according to any claim 11, further comprising a magnetattached to at least one of the first impeller and the second impeller.16. A flow generator according to claim 1, wherein the flow generator isconfigured to generate a flow of about 40-60 l/m.
 17. A flow generatoraccording to claim 15, wherein the flow generator is configured togenerate a flow of about 50 l/min.
 18. A flow generator according toclaim 1, wherein the flow generator is configured to generate a pressureof about 2-12 cm H₂O.
 19. A flow generator according to claim 18,wherein the flow generator is configured to generate a pressure of about6 cm H₂O.
 20. A flow generator according to claim 1, wherein the atleast one outlet comprises two outlets.
 21. A flow generator accordingto claim 20, wherein the two outlets are arranged substantiallysymmetrically around the housing.
 22. A flow generator according toclaim 1, wherein the at least one outlet has an oval or elliptical crosssection.
 23. An apparatus for delivering a flow of pressurizedbreathable gas to a patient, comprising: a flow generator according toclaim 1; a casing to contain the flow generator, wherein the casing isconfigured to engage a part of the patient's body; a power supply forthe flow generator; at least one delivery conduit to convey the flow ofpressurized breathable gas; and a patient interface to receive the flowof pressurized breathable gas from the at least one delivery conduit anddeliver it to the patient's airways.
 24. An apparatus according to claim23, wherein the power supply is contained in the casing.
 25. Anapparatus according to claim 23, wherein the power supply comprises abattery.
 26. An apparatus according to claim 25, wherein the batterycomprises a plurality of battery cells.
 27. An apparatus according toclaim 26, wherein the battery cells are flexible.
 28. An apparatusaccording to claim 25, wherein the battery is rechargeable.
 29. Anapparatus according to claim 23, further comprising a controller tocontrol the power supply.
 30. An apparatus according to claim 29,wherein the controller comprises a voltage regulator.
 31. An apparatusaccording to claim 23, wherein the at least one delivery conduit isformed of silicone rubber.
 32. An apparatus according to claim 23,wherein the at least one delivery conduit is connected to the flowgenerator by a soft grommet or a bellows.
 33. An apparatus according toclaim 23, wherein the at least one delivery conduit comprises aretractable conduit.
 34. An apparatus according to claim 23, wherein thecasing is curved in direction from a front end to a back endcorresponding to a front of the patient's head and a back of thepatient's head, respectively.
 35. An apparatus according to any claim23, wherein the casing is curved from a first side to a second sidecorresponding to a first side of the patient's head to a second side ofthe patient's head, respectively.
 36. An apparatus according to claim23, wherein the patient interface is configured to sealingly engage thepatient's airways.
 37. An apparatus according to claim 23, wherein thepatient interface is configured to not sealingly engage the patient'sairways.
 38. An apparatus according to claim 23, wherein the at leastone delivery conduit comprises a strap attachment portion configured toreceive a portion of a strap of a headgear.
 39. An apparatus accordingto claim 23, further comprising a strap that is configured to encircleat least a part of the patient's body, wherein the flow generator isconnected to the strap.
 40. An apparatus according to claim 39, whereinthe strap is configured to encircle the patient's arm.
 41. An apparatusaccording to claim 39, wherein the strap is configured to encircle thepatient's chest.
 42. An apparatus according to claim 39, wherein thestrap is integrally formed with the casing.
 43. An apparatus accordingto claim 39, wherein the power supply is connected to the strap.
 44. Anapparatus according to claim 23, further comprising a headgearconfigured to support the flow generator.
 45. An apparatus according toclaim 44, wherein the headgear comprises a skull cap.
 46. An apparatusaccording to claim 44, further comprising insulating material providedin the headgear configured to reduce the sound power emitted by theapparatus.
 47. An apparatus according to claim 46, wherein the soundpower emitted by the apparatus is less than about 50 dB(A).
 48. Anapparatus according to claim 23, further comprising insulating materialprovided in the casing and/or the patient interface configured to reducethe sound power emitted by the apparatus.
 49. An apparatus according toclaim 48, wherein the sound power emitted by the apparatus is less thanabout 50 dB(A).